1. Field of the Invention
This invention relates to ligament anchor systems and particularly to endosteal devices for use in arthroscopic surgical procedures to the knee that involve repair or replacement of an anterior or posterior cruciate ligament.
2. Prior Art
In the discipline of arthroscopic surgical procedures for repair and replacement of an anterior or posterior cruciate ligament it is often the practice to form tunnels through the distal femur and proximal tibia ends, across the ligament connection sites or points of origin, both tunnels extending through the bone cortexes. The patient's skin is opened to expose both tunnel ends and the adjacent bone cortex surfaces and a ligament is drawn through the tunnel. The ligament ends are then secured, as with a staple, or the like onto the adjacent cortex surfaces. A U.S. patent application Ser. No. 235,194, of the present inventors, entitled "Channel Ligament Clamp and System" shows such a device for securing a ligament end onto a bone mass. Additionally, other arrangements for attaching ligament ends are shown in a United Kingdom Patent No. G.B. 2,084,468A; and in an earlier patent of the present inventors U.S. Pat. No. 4,772,286.
Distinct from those earlier arrangements that involve securing a ligament beyond both tibial and femoral tunnel ends, an earlier patent of the present inventors, U.S. Pat. No. 4,870,957, and a U.S. patent application Ser. No. 07/465,914, of the present inventors, entitled "Endosteal Fixation Stud and System", provides for securing a ligament end to one tunnel cortex end that does not require opening the skin to that tunnel end. The present invention, similar to these systems, provides for endosteal fixation of a ligament end within a bone mass without the necessity of opening the patient's skin to that tunnel end. Unique therefrom the present invention employs a screw for turning in a threaded tunnel end or a nail or peg for securing it in an unthreaded tunnel end. Neither of which need to break the cortex surface at one tunnel end. The screw is for axial turning in a mount whereto a ligament or tendon is secured. The screw threaded end is turned into a tapped tunnel end that is formed in a bone endosteum. The nail or peg includes the ligament mount secured thereto and is for driving into an untapped tunnel end.
Neither screws having lag screw type threads nor nails or pegs with flexing ribs are new to orthopedic usage. A patent to Lundholm, U.S. Pat. No. 2,570,465, shows such a screw for holding bone pieces together and such nails or pegs are common for implants, such as knee prosthesis, and one such peg that is available as part of a knee prosthesis from TRICON.TM. is known as a FLEX-LOK.TM. peg. A combination of a screw for fitting axially to a ligament mount, or a nail or post mounting a ligament end axially thereto is, however, believed to be new as an endosteal ligament anchor.